Ethyl chloroformate → 1-(4-Chlorophenyl)-1,4-dihydro-3-methylsulfonamidocarbonyl-4-oxo-6-methylpyridazine

Participants

Reaction Conditions

Reaction Steps

To a mixture of 1.3 g of 1-(4-chlorophenyl)-1,4-dihydro-4-oxo-6-methylpyridazine-3-carboxylic acid and 0.73 ml of triethylamine in 50 ml of THF was added at -40° C., 0.53 ml of ethyl chloroformate, and the resulting mixture was allowed to reach room temperature over 2 hours with continued stirring. The mixture was then cooled to -78° C., and the monolithium salt of methanesulfonamide (prepared from 18 mmole of lithiodiisopropylamide and 15 mmole (1.42 g) of methanesulfonamide) in 25 ml of THF was added dropwise at -65° C. The resulting slurry was allowed to reach room temperature with continual stirring. After an additional hour of stirring the reaction mixture was diluted with 200 ml of ether and washed with 1N hydrochloric acid. The ether layer was then extracted with 5% sodium bicarbonate and the aqueous phase was acidified to pH2. The resulting precipitate was collected by filtration and recrystallized from methanol to yield 1.206 g of product, m.p. 225°-227°.

Provenance & Evidence